"Freeeeeee Loadin'...." - isn't that a Tom Petty track?.

From what I can gather, it's not illegal because there's no central server involved with this. We are effectively connecting to each other as pals would do. However, I can't see how that works as copying any copyright material without permission is illegal. Different rules seem to apply to different countries so the idea is, copy like hell before it gets shut down. Perhaps someone else may have more precise information so if they do, could they please clarify.